Method of and apparatus for elimination of condensate in compressed gases



Sept. 11, 1962 G: D. BRADSHAW 3,053,247

METHOD OF AND APPARATUS FOR ELIMINATION OF CONDENSATE IN COMPRESSED GASES Filed June 24, 1959 GRANT D.BRADSHA\M TTORNEYS. I

Uite tte METHOD OF AND APPARATUS FOR ELIMINA- TION F CGNDENSATE IN COMPRESSED GASES Grant D. Bradshaw, Beaver, Pa., assignor to Bradshaw & Company, Pittsburgh, Pa., a corporation of Pennsylvania Filed June 24, 1959, Ser. No. 822,590 6 Claims. (Cl. 126-110) This invention relates to the use of compressed gases in which liquid in the vapor phase may be present, and is for a method of and apparatus for preventing the formation of condensate in such a system.

The invention is especially applicable to the elimination of condensate in compressed air which is supplied to air-driven tools, and will be particularly described in this connection, but it will be understood that this is by way of illustration and does not limit the invention to such application.

Air from a compressor is generally passed through a cleaner before it is carried through pipes or tubes to the tools where it is used. The cleaner functions to eliminate edi rt and foreign substances and liquid that may be present as condensate at that time. However, moisture in the vapor phase will be carried through the cleaner. As the air loses heat of compression, or outside temperature drops, or encounters a place where the line pressure drops and expansion occurs, or at the tools themselves, resulting in a drop in temperature, this vapor may condense and the resulting water be objectionable or interfere with the operation of the tools, or in exposed lines in cold Weather such condensate may freeze and the resulting ice interferes with the intended use of the air or other gas.

The present invention has for its primary object to provide a method of and apparatus for preventing such condensation and assuring that the air or other gas will be delivered to the apparatus or equipment where it is ultimately used or expanded free of condensate. A further object of my invention is to provide a simple, inexpensive, self-regulating method of and apparatus for accomplishing this purpose.

These and other objects and advantages are secured by my invention which may be more fully understood by reference to the accompanying drawing in which the figure is a schematic illustration of an apparatus embodying my invention for practising my method.

In the drawing, 2 designates a compressor which delivers air or other gas through a pipe 3 to a conventional gas cleaner 4 in which foreign substances and any previously condensed moisture or liquid are removed. According to the present invention the air, after leaving the cleaner through pipe 5, passes through a heater 6 before entering the pipe 7 from which lead one or more branch pipes 8-, 9 and 10 that deliver the compressed air or other gas to the tools or other appliances in which the compressed gas is used, these tools or appliances being schematically indicated at 8', 9' and 10' respectively. The heater may be of any suitable form, preferably comprising a casing containing insulation, and in which there is a resistance heating coil as indicated at 11. Current is supplied to the heating coil through wires 12 and 13 connected to a source of current (not shown). The Wire 18 is connected to the source of current through a thermostat 14. According to the present invention the pipe 7 is continued beyond the last branch pipe 10' and terminates in a small restricted nozzle or bleed orifice that directs a current of air against the responsive element 14 of the thermostat.

With this arrangement the air leaving the orifice 15 is at the end of the system so that it maintains a continuous circulation of air through the system, although 3,053,247 Patented Sept. 11, 1962 the volume of air so vented may be very small. This in itself is a desirable condition. The air operating against the thermostat 14 will cause the thermostat to close a circuit to the heater if the temperature of the air falls below a predetermined point. Thus the escaping air from the nozzle 15 with the thermostatic control 14 assures the maintenance of a predetermined temperature in the air. This temperature is kept at a point where the vapor, such as the moisture vapor in the air, remains in a vapor phase and cannot condense. The expansion which occurs at the nozzle 15, simulates the expansion that occurs in any of the tools connected to branches 8, 9 and 10, and therefore if the temperature is kept warm enough to pre vent moisture at the discharge side of the bleed orifice or nozzle 15, it will likewise prevent the condensation of moisture when the air expands into tools connected to any of the branch pipes. At the same time heat Will not be supplied when it is not needed, and the air will be prevented from being heated to an unnecessarily high degree. If the ambient temperature falls, increasing the rate at which the air or other gas loses heat in the system, the temperature drop will be reflected at the nozzle 15, cansing the thermostat to increase the heating current to the heating unit 6. Thus the conditions will be stabilized irrespective of fluctuations in the ambient temperature, or to changes that occur in the temperature drop in the gas through radiation, expansion, or otherwise.

While I have shown and described one particular system, it will be understood that various changes and modifications may be made within the contemplation of my invention and under the scope of the following claims, and that various refinements may be included.

I claim:

1. A compressed gas system comprising a source of gas under pressure, a conduit for supplying gas to a device for utilizing the same, means for heating the gas as it flows from the source to the conduit, a thermostat exposed to atmospheric pressure for controlling the heater, and nozzle means for discharging a jet of gas from the same conduit directly against said thermostat whereby the thermostat is affected by the drop of temperature resulting from the expansion of the gas in said jet.

2. A compressed gas system comprising a compressor, a cleaner into which the compressor delivers compressed gas and which removes condensate produced by the compression of the gas, a heater connected to the cleaner into which the gas flows from the cleaner, a thermostat for controlling the heater and exposed to atmospheric pressure, a duct leading from the heater terminating in a restricted orifice which directs a stream of gas against the thermostat whereby the thermostat is affected by the temperature drop produced by the expansion of the stream of compressed gas emerging from the orifice, and a branch pipe for supplying gas to a device for utilizing the same leading from the duct at a point between the heater and the orifice.

3. The method of avoiding condensation of vapor in a system for transporting and utilizing a compressed gas which comprises heating the compressed gas in the system to a temperature above the temperature at which Water vapor therein will condense upon sudden reduction in the gas pressure to atmospheric pressure, continuously bleeding some of the gas from the system through a continuously open restricted bleed orifice positioned to maintain circulation through the system, and regulating the heating of the gas by the decrease in gas temperature resulting from the expansion of the gas upon its discharge from the orifice.

4. The steps in the method of utilizing compressed air in an appliance which comprises moving air which has been compressed from a compressed air source through a heater and a duct to a continuously open bleed orifice to maintain a continuous flow of air under pressure through the duct, utilizing air for the appliance by withdrawing it from the duct intermediate the heater and the orifice, and utilizing the temperature drop of the air upon leaving the orifice to control the heater and maintain the temperature of the air directly upon discharge thereof from the orifice at a temperature above that at which moisture vapor in the air will condense at the discharge side of the orifice, and utilizing the temperature drop of air upon discharge from the orifice to control the temperature of the compressed air supplied to the appliance and to said orifice.

5. In a system for utilizing compressed air, a source of air under pressure, an air heater through which air passes from said source, a duct for carrying air from the heater, the end of the duct remote from the heater having a bleed orifice therein, a pipe leading from the duct intermediate the heater and the bleed orifice for supplying air to an appliance, and temperature-responsive means against which the discharge of air from the bleed orifice impinges directly for controlling the heater for maintaining the temperature of the air upon expansion in the ap- 4 pliance to be supplied above the temperature Where moisture contained in the air will condense in the appliance.

6. In the method of utilizing compressed air in an airoperated appliance to prevent condensation of moisture in the appliance upon expansion of the compressed air in the appliance the steps which comprise conducting air under pressure through a duct to the appliance, continuously bleeding some of the air from the duct to preclude stagnation of the air in the duct, maintaining the temperature of the compressed air above the temperature at which moisture will condense in the appliance upon expansion of the air utilized in the appliance, and utilizing the temperature drop in the air which is bled from the duct to control the temperature of the compressed air in the duct.

References Cited in the file of this patent UNITED STATES PATENTS 495,071 Thomson Apr. 11, 1893 569,944 Short Oct. 20, 1896 1,708,580 Kerlaouezo et al. Apr. 9, 1929 

